The first phase of this work has concentrated on the preparation of antisera to Herpes simplex virus types 1 and 2 for use in the peroxidase-antiperoxidase (PAP) immunocytochemical technique. Antisera have been obtained which can differentiate the two types of HSV in paraffin sections of infected mouse CNS. Expression of viral antigens will be studied in the CNS of unimmunized mice and of mice immunized with the homologous or heterologous HSV type. The long range goal of this project is the understanding of the mechanisms of demyelination in viral infections of the CNS, the mechanisms of immunity to these infections, and the relationship between these two phenomena.